1. Field of the Invention
The invention relates to a remote vehicle starter and, particularly to a remote vehicle starter for starting an engine of a vehicle remotely and wirelessly.
2. Description of the Related Art
Recently, a remote vehicle starter has been practically used for starting an engine of a vehicle, remotely controlling by a transmitter. This remote vehicle starter establishes various starting permission conditions considering the safety or security when remotely starting the vehicle. For example, there is provided a device that prevents the engine from starting if a door is opened or a brake lamp is lighted when an instruction for starting the engine is received from the transmitter (See JP 2000-25573 A).
A microcomputer judges the engine starting permission conditions. Concretely, the microcomputer inputs and judges information received from a sensor, which will become the engine starting permission condition, according to a voltage level. Accordingly, mainly in the winter time, if a battery voltage decreases, an output voltage of a sensor input to the microcomputer are also lowered, so that the microcomputer may misjudge the information in the remote starting.
For example, a door curtsy switch that detects the opening and closing state of the door, in general, is set to OFF when the door is closed and to ON when the door is opened. An output voltage of the door curtsy switch is formed by dividing a battery voltage, for example, it is set to 7V when the door curtsy switch is at OFF and to 0V when the door curtsy switch is at ON. By comparing the output voltage of the door curtsy switch with a threshold value in hardware, the microcomputer, for example, judges whether the door is opened or closed by judging as H state if the output voltage of the door curtsy switch is 3.5V or higher and as L state if it is 1.5V or lower. However, if the output voltage of the sensor becomes a voltage between threshold value voltages that enables judging H/L state as the battery voltage (the power source voltage) goes down, the H/L state of the microcomputer is judged as unfixed, whereby the wrong opening or closing state may be judged.